<!doctype html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport"
        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">

    <script src="https://unpkg.com/vue"></script>
</head>


<template id="abc">

    <div>
        AA
        <slot :customname="mydata">
            <div>{{mydata}}}</div>
        </slot>
        BB
    </div>

</template>


<body>

    <div id="app">

        <mycomponent>

            <template slot-scope="usename">

                <div>{{usename.customname}}</div>

            </template>

        </mycomponent>

    </div>

</body>

<script>

    const app = new Vue({
        el: "#app",
        data: {
            msg: 'm1',
        },
        components: {
            mycomponent: {
                template: '#abc',
                data() {
                    return {
                        mydata: ['a1', 'a2', 'a3']
                    }
                }
            },
        },
    })

</script>

</html>